Some restaurants allow dogs to come inside, although
The other people in the restaurant may not love animals as much as you do, so you should keep your dog on a leash out of courtesy for them. This also helps the servers get around without having a furball underfoot. It is a good idea to keep your dog close to your feet, and preferably under the table. That way he or she is out of the way.
If your dog is especially friendly, you might want to consider training him or her to obey commands in groups. Like people, animals can get overly excited when a lot of humans are around, especially if those humans are showing interest in them. The key to keeping your dog from wreaking havoc in a restaurant is to teach him or her from a young age to settle down when other people are around. If you got your dog later in its life, then you might find this a bit more challenging, especially if the previous owner made little effort to train the dog.
Unless specifically noted, most dog-friendly restaurants prefer not to have the animals on the chairs or tables. Similarly, letting them drink out of restaurant dishes is generally frowned upon, so you are safer bringing your own doggie bowl for food or water. A light plastic dish usually works best for this. If the restaurant uses disposable dishes, then you can probably get away with having your dog poke its nose in to lick up the scraps, but you should put the dish on the floor, rather than bringing your dog up to table level.
One useful piece of advice is to take your dog for a walk before you head to the restaurant. This will ensure both that he or she won't have to pee while you are eating, and that your pet will be at least somewhat tired, ensuring a less active dinner companion. Unless you want to keep the leash tied to your wrist or leg, you should attach the dog to a chair - not the table. Tying your dog to the table could result in food and drinks flying all directions should something suddenly cause the animal to jump up or make a break for it.
In most cases, you will find yourself eating on the outdoor patio. If you have the choice, it is wise to sit near the edge, in order to keep out of the main path of servers and also away from other diners. If your dog starts to bark or other cause a disturbance, you should be willing to pay your bill and leave, taking the rest of your meal home. Taking your dog with you to a restaurant is a privilege that should not be taken for granted, so respect is due to everyone else in the establishment.
Eating out with a dog can be a pleasant way to keep track of your pet without having to put off your own needs. Just remember that no matter where you go, others will be grateful for your courteous attitude.